Kentucky is a state located in the southeastern United States. It is bordered by Illinois, Indiana, and Ohio to the north, West Virginia and Virginia to the east, Tennessee to the south, and Missouri to the west. Nicknamed the "Bluegrass State," for the bluegrass found in many of its pastures, much of the countryside is characterized by rolling hills and carboniferous forests. The state is also known for having the world's longest cave system, Mammoth Cave National Park. It is home to the Kentucky Derby, the renowned horse race held in Louisville each spring.